This invention relates to a new and improved iontophoretic bioelectrode structure incorporating a seal for preventing the leaking of solution when the bioelectrode is placed against a person's skin for use.
Iontophoresis is a technique of delivering ions into a person's skin or tissue by placing a solution or other medium containing the ions in contact with the skin, and applying electric current to the medium. The solution or medium containing the ions is typically carried by a first bioelectrode pouch or receptacle which, for administration of the medicament, is placed against the skin of a person so that the solution or medium is in contact with the skin surface. A second bioelectrode is placed against the person's skin in proximity to the first bioelectrode and electrical current of opposite polarity is applied to the second bioelectrode. In this manner, ions are caused to migrate from the ion carrying medium through the skin of the person. Sample patents where this technique is described are U.S. Pat. Nos. 4,141,359, 4,166,457, 4,419,092 and 4,477,971.
Prior to use, the bioelectrode is maintained and stored in a dry state (without the ion carrying solution). At the time of use, the bioelectrode is placed against the skin at the desired location, and then the solution is added or introduced into the bioelectrode. To accomplish this, structure is provided by which the ion carrying solution can be introduced by the user into the bioelectrode receptacle. Typically, a special structure is provided on the bioelectrode for receiving a solution applicator, and a special applicator structure is provided for supplying the solution to the bioelectrode. Such special structure is employed, among other things, to enable introduction of solution into the bioelectrode without puncturing it. One problem encountered with iontophoresis is that of leakage or spillage of the solution while the solution is being introduced into the bioelectrode receptacle, or while solution is being administered. This could occur, for example, if the bioelectrode is not securely placed against a person's skin so that gaps or openings between the skin and the bioelectrode exist. Then, when the solution was introduced to the bioelectrode receptacle, leakage could occur through these gaps.
One approach to minimizing the likelihood of leakage involves the use of a wettable barrier over the bioelectrode opening or, better yet, a microporous membrane. The membrane would be selected so as not to leak prior to use but yet to allow migration of ions therethrough to the skin upon application of an electric current to the ion carrying solution. The wettable barrier also serves to reduce the chance of leakage, although not as effectively as the microporous membrane. The disadvantage of both of these approaches, however, is the increased cost of providing either the wettable barrier or microporous membrane.